Motor lubricating system



May 9, 193 J. FREISTADTER MOTOR LUBRICATING SYSTEM Filed Aug. 6, 1936Patented May 9,1939 Q 2,157,752

UNITED STATES PATENT OFFICE 2,157,752 MOTOR LUBRICATING SYSTEM JacobFreistadter, Waltham, Mass., assignor to Waltham Watch Company, Waltham,Masa, a corporation of Massachusetts Application August e, 1936, SerialNo. 94,595

'1 Olaims. .(Cl. 172-36) The present invention relates to electricmotors of the hearing, but only into a small length of and means forlubricating the bearings of the the bearing adjacent to the reservoirspace, rotor or armature shafts of such motors. It is' wherefore a largeproportion of the bearing runs particularly concerned with very smallmotors dry and rapid wear occurs. But if the oil-soaked such as thoseused for driving electric clocks, of Wick is put under pressure enoughto force oil into which quiet running is a practically essential atthewhole length of the bearing, the same prestribute, while the conditionsof use are such that sure causes a continuousflow of oil through andregular attention to lubrication needs is impracout of the bearing untilthe quantity under presticable. g sure is exhausted, whereupon thebearing be- In The motors provided for driving domestic eleccomes d y ad We r to the l t f ooseness 06- 1Q tric clocks are designed to run onalternating u s a t r ya ri fly i a d n th of time. current at a rate insynchronism with the re- I have approached the pr m f lubricatingversals of th r t, i h may b full synsuch bearings from a new angle, andhave solved chronism or any selected fraction of synchroit by makin erotor Serve in effect, a p p .1 nism. The rotor pivots of such motorsare of operable to carry a thin film of Oil from the small diameter, inthe order of .12 of a.centimeerVOir Spaces t the D t bearings d P ter,and the clearance between such pivots and greSSiVelY throughout t eentire length of Such the walls of their bearings is in the order of.0005 hearings, in quantities fl e e t to maintain adet 9025 t t Whilespecific dimensions quate lubrication but not enough to drain the oilvary more or 1955 among different makes of mofrom the bearingswasteifully. 'I'hlS conception, 2O

tors, it is the fact that in all such motors the and obelatlve means forCarrying it into effect ratio of bearing clearance t pivot diameter isconstitute the invention for which I hereby solicit relatively large incomparison with larger and patentplotectionc Aeonerete mbodiment of theheavier machines. Such clearances must be principle is illustrated inthe drawing in p large enough to prevent binding and permit cation to atype of motor now used in commercial trance of lubricant; but if toolarge, permit side electric clocksplay of the pivots. Every reversal ofpolarity of the dr awing, the field magnet of the motor causes a lateral1 is a Side elevation c a motor; movement of the rotor to the limit ofthe bearing 2 is a cross Section ugh the rotor axis so clearance;wherefore if the clearances are too of the motor taken on line of e- 1and {:0

large, a disagreeable humming noise is caused shown on alargel Scale; bystriking of the pivots alternately on opposite 3 is a detail SectionalView taken 9 line sides of their bearings with every reversal of the ofI 60 cycle current, Fig. 4 is a perspective view of the iron core of 3:,The necessary manufacturing tolerances in the the rotor Showing thedisposition of t e masses of diameters of such pivots and bearings aresuch iron by which a constant p oca ion of the th t h a pivot of th l tdiameter haprotor and its pivots is maintained whenever the pens to beassembled with a. bearinglof the largmotor runsest diameter within therange of tolerances, the. Like reference characters designate the same40 clearance may be nearly wide enough to permit part5 Wherever y 000111in all the ures. 43 of th obje tionabl noi b i r d d even The motor hereshown is of the self starting when the motor is' new. And even in thebest Synchronous p adapted to u at a fraction of conditions it needsonly a small amount of wear full synchronous. Speed When excited y e tomake the bearings loose enough for noisy side hating ellrrehh ItComprises a d et 9 slap to occur. provided with exciting coils II andshaded poles 45 Prior means of rotor pivot lubrication in such of wellknown character. the shadi g coils of motors have not been effective toprevent such which are shown at l2. The rotor or armature wear fromtaking place much too rapidly. It consists of an iron core 13 mounted ona shaft It has been the practice to confine a body of oiland having aneven number oi radial notches in soaked wicking or felt in spacescontiguous to itscircumference, between which are projections 50 thebearings in the hope that oil would flow l5 constituting salie t Polesby which the'rotathence between the relatively moving surfaces. tionalrate of the rotor is held to a definite and But such means have notproved satisfactory. fixed ratio with respect to the periodicity of theOil does not flow by capillary or entrain ent of alternating current.Such notches are filled, and 5 the rotating pivot throughout the wholgngth the circumference and ends of the core enveloped M in whichstarting torque is developed to bring the rotor from rest up to theprescribed speed when current is turned into the field coils. Suchnon-magnetic masses are preferably formed integral with one another bybeing cast around the core.

0n the ends of the shaft to are integral pivots 86, it which rotate inbearings 98 and i9 respectlvely carried by bridges 20 and 2i which aresecured to the opposite pole pieces or the magnet core in positionsclear of the shading coils l2. The rotor shaft M is extended to aconsiderable distance at one side of the rotor and formed as, orprovided with, a pinion 22 for transmitting rotation to a train ofreducing gears by which the hands of a clock may be driven. The hearing89 is supported from bridge 26 by a potence 253 to aiforrl. space forsuch pinion.

Caps 2d and 25 are mounted and fitted tightly on the outer ends of thehearings 08 and is.

'l hey provide enclosed spaces or oil reservoirs contiguous to the endsof the bearings and into which the-shaft pivots project more or less.Preferably wiclrs 26 and 27s, of any suitable fibrous material andconstruction, are placed in the oil reservoirs to hold the oil andprovide capillary shaft ends and the bearings, and between the pivotextremities and the caps El and 25 wide enough to permit a substantialmovement of the rotor. And the rotor is provided with means for causingit to reciprocate axially, with constant and regular repetition of its'movements, whenever and as long as the motor is in action.

The means for so reciprocating the rotor consists of masses of iron 2E,29 disposed on the rotor in such manner as to change the-magneticbalance of the rotor with respect to the field with each quarterrotation; but they are mechanically balanced on opposite sides of thepivot axis so as not to cause any lateral vibration. As here shown, suchiron masses are shallow segments on one end of the core l3, integraltherewith, and preferably formed by cutting a wide and shallow groove ofuniform depth diametrically across one end face of the core.) Theboundaries of such groove are parallel to one another and equallydistant from the axis at opposite sides thereof. However, the specificdetails 01' these masses and the specific method of forming them hereshown is" not the' prime essential of the invention, for they may bemade or applled otherwise and 10- oated in other positions. r

By virtue of the magnetic unbalance thus produced, the transverse planeof the core midway between the outer faces of the masses 28 and 29 andthe opposite face of the core is brought by magnetic actionsubstantially into coincidence with the plane midway between the lateralbounding faces of the magnet poles whenever the. masses 28, and 29 arein register with the poles, while the plane midway between the bottom ofthe shallow groove previously defined and the opposite face of the core,is brought into substantial coincidence with the median plane of thefield magnet whenever. the masses 28 and 28 register with the lnterpolarspaces of the magnet. Thus the entire rotor structure is shifted backand forth axially a distance substantially equal to half the axialprojection of such masses during each 90 of rotation. The

pivots are thereby advanced into and retracted from the oil reservoirspaces. when advanced into such a space the pivot picks up a film of oilwhich, in its next retraction, it carries into the bearing. Part of theoil film so displaced adheres to the bearing surface and is applied toan adjoining zone of the plvot when the latter is next advanced. Minutequantities of oil are thus successively withdrawn from theoil reservoirand successively carried and applied to zones of the pivots and bearingsurfaces more and more remote from. the reservoirs, whereby oilsufficient for lubricating the entire length of the bearingsis'constantly supplied and renewed, and wear of the pivots and bearingspreventedior a greatly extended length of time. But the transfer of oilis not great or rapid enough to cause any accumulation at the inner endof the hearing or dripping and wastage of oil therefrom.

In the motor illustrated herein the distance of endwise reciprocation is935 centimeter. I have found this adequate for the purpose; but ofcourse do not limit the protection which I claim to a displacement ofany specific amount,

ior the extent of such movement may be widely varied and made ofany'desired value to fit particular circumstances.

The oil in the reservoirs is not put under pressure, but reliance isplaced solely on the pumping effect of the pivots to distribute it overthe bearing surfaces. Consequently there is no flow and wastage of oil,but the supply is conserved in the greatest possible measure.

The foregoing explanation of the invention with reference to specificuse in a clock motor is not toe construed as a limitation of theprotection claimed either to that specific use or f to self startingelectric motors or even to synchronous motors. On the contrary, I claimprotectlon for all useful applications of the principies as well as thedetails of the invention. I consider that the broad principle includesthat of distributing oil in a shaft bearing by controlled endwisemovement of the shaft plvot or trunnion, whether such movement isproduced magnetically or by other means, and whether the machine inwhich it is effected is a prime mover or is otherwise driven.

What I claim and desire to secure by Letters Patent is:

1. The combination with a supporting struc ture having a bearing and arotor having a pivot portion contained rotatably in said bearing andbeing movable endwise therein, of an oil reservoir contiguous to theouter orifice, of said bear-- ing into which the extremity of said pivotis adapted to protrude, and means for giving to the rotora back andforth axial reciprocation simultaneously with its rotation, such as tocause alternate advance of the pivot into and withdrawal from saidreservoir, whereby to effect transfer of oil through the bearing.

2. A machine comprising a stationary structure having alined bearings, arotor having alined 6 from the reservoir into and ducing a periodic backand forth endwise movement of the rotor in the course of its rotationsufficient to cause advance and retraction of portions of the pivotsinto and out of the oil supplies respectively contiguous to them.

3. A motor comprising a supporting structure having separated alinedbearings, oil holding means mounted contiguous to the respective outerorifices of said bearings, a rotor structure having oppositelyprotruding alined pivots fitted to rotate and move endwise in saidbearings and protruding at their outer extremities into the oil holdingmeans, said supporting structure and rotor being complementally soformed as to permit endwise movement of the entire rotor including itspivots, and means for effecting back and forth endwise movement oftherotor simultaneously with rotation thereof.

4. An electric motor comprising a fleld magnet, a rotor including aniron coreadapted to revolve between the poles of said magnet; bearingsconnected to said magnet having enclosed oil containing spacescontiguous to their outer ends, a rotor shaft on which said core ismounted having pivots fitted to rotate and reciprocate in said bearings,said shaft pivots and bearings being relatively so located as to supportthe core between the magnet poles and being constructed to permit axialdisplacement of the core in both directions from a mid position, saidcore being so magnetically unbalanced that'the action of said magnetcauses it to move back and forth endwise during each rotation.

5. An electric motor comprising a field magnet, a rotor having an ironcore and a shaft, bearings connected with said magnet in position tosupport said shaft rotatably with the core between said magnet poles,the rotor core and shaft being free to move 'endwise with respect to thebearings, means for holding a supply of oil in contact with parts ofsaid shaft which occupy said bearings, and magnetically unbalanced ironmasses associated with such core in a manner to effect back and forthreciprocation of the core by magnetic action during the rotation of thecore.

6. An electric mptor comprising a stator having bearing and a rotorhaving pivots supported rotatably and reciprocatively in said bearings,the cooperating magnetic elements of said stator and rotor being in acondition of unbalance axially of the rotor such as to cause back andforth reciprocation of the rotor during its rotation, combined withmeans for delivering oil to a subordinate part of the length of saidpivots, the reciprocating movement of the pivots being effective todistribute oil throughout substantially the entire extent of the bearingsurfaces.

7. An electric motor comprising a field magnet a rotor having an ironcore and a shaft, bearings connected with said magnet in position tosupport said shaft 'rotatably with the core between said magnet poles,and means for maintaining a supply of oil in contact with parts of saidshafts which occupy said bearing, the rotor core and shaft being free tomove endwise with respect to the bearings and the core having axiallyprojecting iron masses at one end spaced apart from one another but inmechanically balanced relation to one another at opposite sides of therotor axis. 1

JACOB EREIBTAIUI'ER.

